Join Date: Dec 2008
Location: Under the Downunder
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Originally Posted by robow
For those in the know, is there any significant difference between 6061 and 7005 aluminum alloy tubing that might create a superior frame for say cyclocross ? Are there many inherent differences ? Thank you for your insights.
In layman's terms 7005 is stronger than 6061 (for bicycle frame building applications almost a parallel between chromoly and high tensile steel). The extra strength of 7005 allows for thinner wall thicknesses and therefore a lighter frame. Butted and double butted aluminium tubes are usually 7005 for this reason. Building a 7005 frame with the same tubular wall thicknesses as those utilized for a 6061 frame defeats the purpose as the frame would weigh the same and the advantage is lost. During heat treatment, 7005 is tempered with a sudden blast of cool air, whereas 6061 is dunked in water (I hope I got that one right and not the other way around!)
Now here's what's interesting... in one of my factory visits in China, I asked the very same question. Somewhere along the conversation of heat treatment (and various sushi and beer type comparisons between the west and east), I asked "does the heat treatment or temper (T6) in aluminium last forever?" The answer was a rather casual, no!
Now I'm kicking myself here, because I wasn't really listening (maybe I got distracted by the prospect of eating the turtle soup
)... but the temper apparently diminishes in time, like it self-anneals or something. Don't ask me how many years, but just in case you want to bequeath the frame to your grandson or something, it might pay to check this aspect in your research. One of them lasts a heck of lot longer than the other, I'm just not sure which one it is.
Please bear in mind that this is what I've been told and I have not had the time or the need to verify the information. So if you find out, please kindly post back and let us know.
Funny that, suddenly I feel like having some sushi...